The present invention relates to methods and systems of operating a redundant transmission line, and more particularly to a method and system of operating a redundant transmission line having a redundant construction formed of a multiplexing redundant unit or the like.
In a conventional transmission system having an active system and a reserve system which is formed of optical interface boards using a multiplexing transmission unit or a cross connect, the reserve optical interface board performs the same process as the active optical interface board. This arrangement comes from a need to always stand by for a failure in the active system. However, in a majority of cases, there is no need to use a reserve system, and the active system meets all the operating needs. For this reason, it will be possible to reduce the power consumption of the reserve system by allowing the reserve system to carry out processes less frequently than the active system. The focus of the present invention is to limit the power supply to the reserve system, which is actually used relatively infrequently, so that the power consumption of the entire transmission apparatus having a redundant construction is reduced.
FIG.1 shows the redundant construction of a conventional transmission system. It is assumed that the transmission apparatus A and the transmission apparatus B shown in the figure are of the same construction. Each of the transmission apparatuses A and B includes an active optical interface board 100a, a reserve optical interface board 100b, a selection part 200 for switching the optical interface boards 100a and 100b to either an active system or to a reserve system, and a power supply part 300 for supplying the power to the optical interface boards 100a and 100b.
FIG.2 shows the construction of the optical interface board in the conventional transmission apparatus. The optical interface board 100a (100b) includes an optical/electrical signal conversion part (O/E) 130, an electrical/optical signal conversion part (E/O) 140, a transmission line signal processing part 110, and an apparatus interface 120.
The O/E 130 converts a 150 Mbit or 50 Mbit optical signal transmitted via a transmission line into an electrical signal. The E/O 140 converts an electrical signal from the transmission line signal processing part 110 to an optical signal and forwards the optical signal to the transmission line.
The transmission line signal processing part 110 includes: a frame synchronization part 111, a transmission line error detection part 112, an overhead detection part 113, a pointer detection part 114, a transmission error detection signal attachment part 115, an overhead attachment process part 116, and a pointer attachment process part 117. FIG.3 shows the construction of the apparatus interface within the conventional transmission apparatus. The apparatus interface 120 includes an apparatus pointer processing part 121, an apparatus error detection signal attachment part 122, a frame timing stamp (FTS) attachment part 123, an FTS detection part 124, an apparatus error detection part 125 and an apparatus pointer detection part 126.
Referring to FIG. 1, the selection part 200 makes a determination as to whether an optical interface board is to be used in the active system or the reserve system. In the example shown in the figure, the optical interface board 100a is allocated to the active system, and the optical interface board 100b is allocated to the reserve system. A description will be given, with reference to FIGS.2 and 3, of the operation executed when the transmission apparatus A is a sender and the transmission apparatus B is a receiver. The sender transmission apparatus A accepts a signal delivered from within the apparatus via the apparatus interface 120. The apparatus interface 120 attaches a pointer, an overhead and transmission line switching information to the data by means of the apparatus pointer processing part 121, before sending the data to the apparatus error detection signal attachment part 122. The apparatus error detection signal attachment part 122 processes the data so as to attach thereto a transmission line error detection signal, before sending the data to the frame timing stamp attachment part 123. The frame timing stamp part 123 attaches a frame timing stamp to the signal to be transmitted, before sending the signal to the receiver transmission apparatus B.
The receiver transmission apparatus B receives the signal from the sender transmission apparatus A via the transmission line. The O/E part 130 of the transmission apparatus B receives an input of the 150 Mbit/s or 50 Mbit/s optical signal from the transmission line and subjects the signal to optical/electrical conversion. Thereafter, the signal is input to the transmission line signal processing part 110. It is to be noted that a serial optical signal input from the transmission line is converted into a parallel signal. The frame synchronization part 111 synchronizes the signal which has been converted into a parallel signal. After the synchronization, the frame synchronization part 111 outputs the parallel signal to the transmission line error detection part 112. The transmission line error detection part 112 checks the signal input from the transmission line for a failure in the transmission line, and sends the result to the overhead detection processing part 113. The overhead detection processing part 113 detects an overhead in the signal, and sends the result to the pointer detection processing part 114. The pointer detection processing part 114 detects a pointer in the frame, and sends the result to the apparatus interface 120.
The receiver transmission apparatus receives a signal transmitted from the transmission line signal processing part 110 via the apparatus interface 120. The frame timing stamp detection part 124 detects a frame timing stamp in the received signal. The signal is then sent to the apparatus error detection part 125. The apparatus error detection part 125 detects an error in the signal, and sends the signal to the pointer detection signal 126. The pointer detection part 126 detects a pointer in the signal, and transfers the signal to the apparatus.
In the transmission apparatuses A and B, the active optical interface board 100a and the reserve optical interface board 100b perform the same process. Referring to FIG. 1, the signal sent from the active optical interface board 100a of the transmission apparatus A is transmitted via an active transmission line 20 and is input to the active optical interface board 100a of the transmission apparatus B. The signal sent from the reserve optical interface board 100b of the transmission apparatus A is transmitted via a reserve transmission line 30 and is input to the reserve optical interface board 100b of the transmission apparatus B.
In the transmission apparatuses having a redundant construction as shown in FIG. 1, the power supply part 300 supplies the power to the active optical interface board 100a and the reserve optical interface board 100b so that the active optical interface board 100a and the reserve optical interface board 100b can be operated. The power from the power supply part 300 is evenly supplied to the optical interface boards 100a and 100b. Accordingly, the power is supplied to the active and reserve optical interface boards 100a and 100b at a ratio of 1:1.
Since the above described conventional method of operating the transmission line allows the power to be evenly supplied to the active optical interface board and to the reserve optical interface board, and the reserve optical interface board and the active optical interface board perform in an identical manner in processing the signal transmitted on a transmission line, there is a problem in that the power supplied to the reserve system is wasted when the active system is being normally operated.